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Old 11-17-2013, 05:23 AM   #31
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I Googled for materials on liners and it's the ABC, Alu /Brass/Chrome
When lapping a liner, your thinning out the hard Cr coating, doesnt make me happy. I do understant the N12T1 class, we use an OS TG / JAMMING < 1 HP in our "gas touring" and they are budget engines. They proved too fast for the "choked" 4mm OSTG class and we cant use them unfortunately.

Does anyone ever do work on their pistons to make them fit. Precision lathes etc, or are the tolerances so small it's not viable?

h


More Google.
Other types (and OS is the worst example) is ABN where N is for nickel plating, AAO (as used by Norvell and I think will be the next big thing) which is Aluminium piston with an Aluminium Oxide coating on the aluminium liner. Al Oxide is somewhere between chrome and diamond for hardness

I think
The best sleeves I ever had the pleasure to run were EdwardN's Beryllium Sleeves.
Too bad he's not making them anymore, they were almost indistructable...
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Old 11-17-2013, 05:30 AM   #32
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The most important thing of handpicked engines is the correct angle between the holes for crankshaft and sleeve in the crankcase.

We are lucky enough to get such hand selected engines and they are a breeze to break in, go like hell and last very long.
These engines are also very easy on the bearings.

All it takes to mess up such an engine is a loose engine mount screw or uneven engine mounts. The crank case can be distorted and the engine goes average quickly :-(

Thats why I spent a god bit of time to make sure the engine mounts are really flat and level and I also tighten the engine mount screws with a torque wrench, so the oad spreads evenly...
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Old 11-18-2013, 02:21 AM   #33
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The best sleeves I ever had the pleasure to run were EdwardN's Beryllium Sleeves.
Too bad he's not making them anymore, they were almost indistructable...
Beryllium is the chemical element with the symbol Be and atomic number 4. Because any beryllium synthesized in stars is short-lived, it is a relatively rare element in both the universe and in the crust of the Earth. Wikipedia
Symbol: Be
Electron configuration: [He] 2s2
Atomic number: 4
Electrons per shell: 1,2
Atomic mass: 9.012182 0.000003 u

That's very rare and light, it's a coating in the combustion chamber ?
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Old 11-18-2013, 03:04 AM   #34
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Beryllium is the chemical element with the symbol Be and atomic number 4. Because any beryllium synthesized in stars is short-lived, it is a relatively rare element in both the universe and in the crust of the Earth. Wikipedia
Symbol: Be
Electron configuration: [He] 2s2
Atomic number: 4
Electrons per shell: 1,2
Atomic mass: 9.012182 0.000003 u

That's very rare and light, it's a coating in the combustion chamber ?
No, it was actually part of the alloy he used for the sleeve. He called it BRB.

Here is their old website, where you can read a short description in the right column: http://www.palmarisracing.com/AboutUs.htm
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Old 11-18-2013, 05:03 AM   #35
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Very interesting site!! I doubt things were hit and miss though, and for that effort, it would have been $$$.
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Old 11-20-2013, 12:37 AM   #36
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So in conclusion, Roelof put forward the only real slution to an engine that's too tight and that is to hone the liner.
Which means one can preserve a tight engine's piston, rod and crank and at least measure up old liners, hone for a better fit and resurrect an old engine and one keeps a fresh liner for another day.

Thanks for the input, the feedback was informative and diverse and personally I learned more than I thought

Thanks

h
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Old 11-20-2013, 01:49 AM   #37
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Originally Posted by blis View Post
So in conclusion, Roelof put forward the only real slution to an engine that's too tight and that is to hone the liner.
Which means one can preserve a tight engine's piston, rod and crank and at least measure up old liners, hone for a better fit and resurrect an old engine and one keeps a fresh liner for another day.

Thanks for the input, the feedback was informative and diverse and personally I learned more than I thought

Thanks

h
Hi Blis,

you can't hone the liner, you'd destroy the chrome layer quickly. The chrome layer also is only a few micrometers thick, not enough to really change the fit of the pistion.

When you "lap" a piston / sleeve set, material from the piston will be removed.

Lapping paste is basically not much different from car polish.
You put a tiny bit on the upper portion of the piston and then you move the piston up and down inside the sleeve while simultaniously rotating it back and forth.

You have to be careful though, depending on how coarse the lapping paste is, this can go very quickly.

Every few strokes, you have to clean piston and sleeves thouroughly and check the fit.

I usually stop, when the hole of the piston pin is half covered by the exhaust window's upper edge.

Hope this helps.

http://www.chemico.co.uk/lappingpaste.html
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Old 11-20-2013, 09:24 AM   #38
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A chrome layer does have some space but indeed with a very tight engine it is better to work on the piston. With an used or re-pinched engine with a tight fit it will help the engine to hone the sleeve because a lot of the hone profile is almost gone.
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Old 11-22-2013, 12:51 PM   #39
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I do belive that working the sleeve, espesially With a long stone is no good... Reasson is that a sleeve will have different taper in the stroke of the piston. That is why i always lap the piston and have had a good friend making me a spesial tool. It Works awsome. My enignes runs longer on a fueltank and brekae in quite easy :-)
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Old 11-22-2013, 01:23 PM   #40
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Originally Posted by stefan View Post
Hi Blis,

you can't hone the liner, you'd destroy the chrome layer quickly. The chrome layer also is only a few micrometers thick, not enough to really change the fit of the pistion.

When you "lap" a piston / sleeve set, material from the piston will be removed.

Lapping paste is basically not much different from car polish.
You put a tiny bit on the upper portion of the piston and then you move the piston up and down inside the sleeve while simultaniously rotating it back and forth.

You have to be careful though, depending on how coarse the lapping paste is, this can go very quickly.

Every few strokes, you have to clean piston and sleeves thouroughly and check the fit.

I usually stop, when the hole of the piston pin is half covered by the exhaust window's upper edge.

Hope this helps.

http://www.chemico.co.uk/lappingpaste.html


What grade of paste do you use?
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Old 11-23-2013, 02:33 PM   #41
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just a FYI.

When a piston is worn out, it is only 0,0015mm smaller in diameter from brand New... Be very careful when you lap Your piston :-)

FYI 2:

Do not use dimond based paste. It can get into the piston material and i very difficult to Wash off.

And lastly, use an old conrod and wristpin. If you get lapping paste between pistonpin and piston or rod, you will ruin pin and rod.

I use this paste: http://stores.ebay.com/E-Z-Bore-Moto...=p4634.c0.m322 but in 2000grit
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Old 11-23-2013, 07:01 PM   #42
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Beryllium is the chemical element with the symbol Be and atomic number 4. Because any beryllium synthesized in stars is short-lived, it is a relatively rare element in both the universe and in the crust of the Earth. Wikipedia
Symbol: Be
Electron configuration: [He] 2s2
Atomic number: 4
Electrons per shell: 1,2
Atomic mass: 9.012182 0.000003 u

That's very rare and light, it's a coating in the combustion chamber ?
this is why we use this material in our NITRO/GAS powered R/C Boats for our props.it is very strong,but east to grind and tweek. I always wounderd if it was the cost,why nobody has ever used NICACIL?? it is used in formula 1 and bike racing.have a friend that was a Team Ducati racer and he told me about this stuff. it would last forever but the piston material would have to be much stronger than the stuff pistons are made from now. I also race boats with a guy who is a machinist and makes pistons for boat motors.he makes them from billet alum and I think 30% silicone.so far he has made pistons up to 1.01.going to see if he will make one for my .12 JP modified,mike.
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Old 11-24-2013, 12:06 AM   #43
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What grade of paste do you use?
Anyone have pics or videos of lapping liners.

Might be good if we have factual measurements of liner chrome thickness, piston wear etc.

And to clarify, Roelof pointed out the hone as a method to re-finish the liner coating for a run-in.

So really how much are we referring to in terms of tight /just run-in/loose.

I assume we'll be in the low thousanths/high ten thousanths right?
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Old 11-24-2013, 05:31 AM   #44
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Nicacil is used in the past but without succes. Yes, on larger engines it is succesfull but the main difference is that large enginges have piston rings so no pinch is needed. The high pressure of the pinch of our enginges (for sure when it is new) is capable of tearing away the nicacil layer. I believe the old HPI Nitrostar 12FE was such an engine and I know Picco has tryed it.
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Old 11-24-2013, 12:51 PM   #45
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Anyone have pics or videos of lapping liners.

Might be good if we have factual measurements of liner chrome thickness, piston wear etc.

And to clarify, Roelof pointed out the hone as a method to re-finish the liner coating for a run-in.

So really how much are we referring to in terms of tight /just run-in/loose.

I assume we'll be in the low thousanths/high ten thousanths right?

See my post, i messured 15 pistons and liners and numbered them. My messuring Device messured With a tolerance of 0,001mm. it is more than 0,001mm and less than 0,002mm that is worn out. So i would Guess that a medium tight fit is abaout 0,0003mm. That is after the first 1 liter of running in.This was a tool i borrwed and cost was araound 1500us dollars. I do not have a good Device to messure sylinders, so i do not know how much they have worn Down ( i.e larger in diameter )
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